Robarms XCR FAQ post
- Thread starter SIGGER
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loki_81: Are you cutting the pmag toward the front or towards the bottom? AR mags (ie: STANAG = standardized) are standards based. There *should* be no difference from one to the next unless your mag well is interfering with the magazine (or vice versa). Especially from a reputable name like Magpul (I might understand if you were buying cheap knock off aluminum mags).
If towards the front it can be rivet problems (is the rivet counter sunk enough to not interfere with magwell). Towards the bottom can be the tightness of the rivet position up and down along the follower path (pinned to 5 vs 5-1/2).
If the rivet in your pmag is not counter sunk enough (ie: totally flush) it will cause fitment issues. (Can't tell from your photo how well the counter sink is, gotta feel it).
Also with the bolt closed and a full magazine, most AR style mag fed rifles will require a "tap" on the bottom to ensure proper magazine seating (fairly hard slap actually). This can be the up/down sensitivity. The tolerances are tight. Depending on whether your pmag is pinned at "exactly 5" or 5-1/2 rounds (a little more than 5 without making an illegal 6 round mag) your mag may be tighter/looser. Have you tested with say 3 rounds in it on an unmodified PMAG just to test this hypothesis? I have some LAR-15 pistol mags which are firmly set at 10 rnds and require a solid tap on the bottom or they won't seat when full with the bolt closed. This is true of the Tavor and many ARs too. If testing with like 3 rounds in the mag works then you know its a magazine tension/pinning issue.
RobArm's machining on the XCR is beautiful and very consistent. Also Magpul is well vetted in the industry. I'd suspect something specific to your setup (and/or Canadian mag pinning) before suggesting to the masses that "all XCRs need modified PMAGs" or that XCR mag wells are inconsistent at all. Thanks to everyone else who backed up that PMAGs work no problem.
So far my XCR has run top notch. 700+ rnds with zero problems in 2 months or so. I'll keep testing to be sure, must shoot more.
As for john frusciante's original question: fitment of beowulf mags won't be the issue so much as follower performance, feeding and jams. Keep in mind they are design for .50 beowulf caliber ammunition for which the XCR currently does not have a conversion kit for. (I know read between the lines, but if RobArms put out a .50 beowulf conversion kit that'd be nice!)
If towards the front it can be rivet problems (is the rivet counter sunk enough to not interfere with magwell). Towards the bottom can be the tightness of the rivet position up and down along the follower path (pinned to 5 vs 5-1/2).
If the rivet in your pmag is not counter sunk enough (ie: totally flush) it will cause fitment issues. (Can't tell from your photo how well the counter sink is, gotta feel it).
Also with the bolt closed and a full magazine, most AR style mag fed rifles will require a "tap" on the bottom to ensure proper magazine seating (fairly hard slap actually). This can be the up/down sensitivity. The tolerances are tight. Depending on whether your pmag is pinned at "exactly 5" or 5-1/2 rounds (a little more than 5 without making an illegal 6 round mag) your mag may be tighter/looser. Have you tested with say 3 rounds in it on an unmodified PMAG just to test this hypothesis? I have some LAR-15 pistol mags which are firmly set at 10 rnds and require a solid tap on the bottom or they won't seat when full with the bolt closed. This is true of the Tavor and many ARs too. If testing with like 3 rounds in the mag works then you know its a magazine tension/pinning issue.
RobArm's machining on the XCR is beautiful and very consistent. Also Magpul is well vetted in the industry. I'd suspect something specific to your setup (and/or Canadian mag pinning) before suggesting to the masses that "all XCRs need modified PMAGs" or that XCR mag wells are inconsistent at all. Thanks to everyone else who backed up that PMAGs work no problem.
So far my XCR has run top notch. 700+ rnds with zero problems in 2 months or so. I'll keep testing to be sure, must shoot more.
As for john frusciante's original question: fitment of beowulf mags won't be the issue so much as follower performance, feeding and jams. Keep in mind they are design for .50 beowulf caliber ammunition for which the XCR currently does not have a conversion kit for. (I know read between the lines, but if RobArms put out a .50 beowulf conversion kit that'd be nice!)
Herron Arms could fix that for you with a .50beo custom barrel and a 7.62x39 bolt if I understand the case dimensions right. However shooting .50beowulf might cause all of that loctite to come loose
.As for the mag fit with Pmag Jaime already cleared that up, thanks. Quick answers are, rivet has been ground to fit, and the mag release hole was cut out, afterward it seated and held quite well. Yes it was tested on an empty mag, four rounds and five all of which the mag could be pulled out, it was pinned at 5.5.
Seems it is as simple as adjusting the mag release. I did hear the same reports with Pmags and XCR so I just cut out the release hole and insta fixed.
Well I've joined the club.. The wife told me I could so I have ordered one in 223.. Will need to sort out optics and some additional mags and figure out the stock changes if I need too...
It's never been as simple as just getting a gun has it..
I have about 20 LAR-15 Mags but they are in storage.. So I ordered 2 for now...
It's never been as simple as just getting a gun has it..
I have about 20 LAR-15 Mags but they are in storage.. So I ordered 2 for now...
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I tried numerous optics on my XCR-L. I finally settled on the Eotech 512. This sight is awesome as it has a large window to make 2 eye, quick target aquisition very easy. The Eotech also co-witnesses perfectly with the Magpul MBUS sights. I chose the 512 because it uses AA batteries which are very cheap, last long and are available everywhere. You may consider one of the other, smaller sights if you are concerned about the weight. As far as mags go, I use any LAR or XCR 10 round pistol mags with couplers.
Just my $0.02... The XCR is not the best rifle choice for "more" range. Like almost any CQB (black) rifle, the XCR is a great firearm for targets up to 100m where close is close enough. This is not to say that you can't use it for 200m+ but there are far better & cheaper options if you are looking for that kind of accuracy. It is kind of like street racing with a pickup truck instead a sports car. It can be done but there are better options. I see and hear of many who are hell bent on getting that perverbial "1MOA" accuracy from their AR. My only thought is: "WHY?" YMMV
I use my XCR/Eotech out to 100 yards. I typically shoot groups inside 4" with the 512 at 100 yards which represents the limits of what my eyes can achive. When I had a 14X scope, I was getting 2"-2.5" groups at the same range. My Tikka T3 Lite gets inside 1" at the same range with the same .223 ammo at 1/3rd the price of the XCR/optics combo. I had the XCR at the range yesterday and as usual, I set my targets at 40 yards. I was getting inside 2" with the Eotech which is typical of my results.
Which groups are you referring to? The 2"-2.5" groups are what I get with a scope at 100 yards. Definately there is a "shooter" factor. I believe the gun is better than that. I believe the gun can do 1.5" at 100 yards with .223 but not better. The other .5"-1" variance would be my skills (or lack thereof). With the Eotech, eyesight is a huge variable since the dot is 1-3MOA depending on the brightness and with no magnification, seeing the target accurately at 100 yards is near to impossible.
The fact is that my Tikka bolt action .223 is still more accurate using the same ammo and the same crappy "shooter". If you are suggesting that your XCR is more accurate than 1.5 MOA, I call BS...
That is representative of my results. This is why I'm confused with Camp Cook's comments. Maybe he compensates for the gun's limitations. I know that with heavily developed hand loads, my cousin achieves very close to 1.5" at 100 yards with his. I don't load ammo and have never had a 5 round group better than 2" at 100 yards with my XCR.
I put about 200 rounds through my new 7.62x39 xcr today and had only 3 out of about 20 mags actually lock up on empty mag. Gas setting was on 4 since shes still on the break in stage but shouldnt she still have bolt lockup? Im using 5 robarms 10rd x39 mags from wolverine supplies.
Out of spec bolt catch is all i can think of. Since it should still lock up on the 4th setting, and with all 5 mags failing eveytime but a few.
Any other thoughts?
Out of spec bolt catch is all i can think of. Since it should still lock up on the 4th setting, and with all 5 mags failing eveytime but a few.
Any other thoughts?
